In the oil and gas industry, devices known as pigs are launched into fluid-transporting pipelines, and typically propelled through the pipeline by the pressure of the fluid being conveyed. Such pigs are used for different purposes, including separation of two different fluids being transported, cleaning the interior wall of the pipeline, and internally inspecting the integrity of the pipeline. The pig is removed from pipeline upon receipt of the pig at a receiver at an end of the pipeline.
A set of valves at the receiver are set into a condition that will convey the pig into a pipe that forms a trap barrel having a normally closed door mounted at an open end of this pipe, and when the arrival of the pig in the trap barrel is detected, the valves are set in a condition sealing off the trap barrel from the pressurized pipe line, and pressure in the trap barrel is vented to atmosphere. With the trap depressurized, the door is opened to enable the operator to extract the pig from the receiver through the open end of the trap barrel.
However, serious injury and even death has been known to occur as a result of unintended and unexpected ejection of the pig under pressure, for example as could potentially occur in the event of an equipment failure. Accordingly, there is a need to prevent or minimize the potential for impact of an operator by a pig forcefully ejected from the opening of the pig receiver.
Examples of manually carried and manually operated tools for extracting pigs from a safely depressurized pig trap can be found in U.S. Pat. Nos. 2,575,146 and 4,759,579, and Canadian Patent Application 2016138, but use of each of these tools places the operator in-line with the opening of the pig receiver, thus potentially placing them at risk.
U.S. Pat. No. 7,954,194 and U.S. Patent Application Publication No. 2011/0174387 disclose wheeled cart-like devices for extracting and transporting large pigs, but may be excessive in size and design complexity for extraction of smaller pigs.
U.S. Pat. No. 3,303,525 discloses a pig retriever that features a tapered basket situated inside the receiver for wedged receipt of a deformable pig within the basket, for subsequent removable of this basket and an attached plunger from the receiver for removal of the deformed pig from the basket using the plunger.
U.S. Pat. No. 5,524,675 teaches a safety device for automatically preventing an injectile in a pipeline from inadvertently escaping the pipeline at a coupling point thereof when the pipeline is decoupled at this point.
Applicant has developed a manually carried and manually operated pig extraction tool and method of operating same that are not disclosed or suggested by prior art and that allow for improved safety during withdrawal of pigs from pipeline receivers.